Question-and-Answer Resource for the Building Energy Modeling Community
Get started with the Help page
Ask Your Question

Jacob Lindblom's profile - activity

2015-04-28 09:01:42 -0500 asked a question Wrong unit in the OpenStudio Space Infiltration Effective Leakage area dialog

The dialog in OpenStudio where to insert the effective air leakage area indicates the unit m2. But the inserted value turns up in the idf-file with the unit cm2. I´m not sure where to post this remark, please let me know if it should be notified in another way.

2015-03-27 16:47:28 -0500 received badge  Teacher (source)
2015-03-27 14:30:36 -0500 answered a question Ground heat transfer data and similar detailed input in Open Studio

Thanks a lot for the answer. I have now tried to write my own measure. During this struggle I was inspired by an existing EnergyPlus measure from the BCL-web (AEDG K12 - SlabAndBasement) which includes "a call" to a short idf-file to include new objects. So I wrote a measure with the following code in the measure run section:

 dummyIdfPath  = OpenStudio::Path.new("#{File.dirname(__FILE__)}/resources/dummy.idf")
 dummyIdf = OpenStudio::Workspace::load(dummyIdfPath).get
 workspace.addObjects(dummyIdf.objects)

Then I can use the e+ IDFEditor to create dummy-files containing whatever objects not covered by OpenStudio and put them in a folder named resources in the measure folder. Preliminary tests indicates that it works. The test objects anyway turns up in the ...run\4-EnergyPlusPreProcess-0-folder.

Amendment: Later I have concluded that the method above is a useful method to add things to the idf before e+ receives it. However does OpenStudio run the ExpandObjects before running the Measure and it is during the ExpandObjects run that the Basement related objects must be present in the idf to have desired impact. My final, slightly simplified, solution to my problem is as follows:

  • Write a short idf-file using IDF-Editor only containing the necessary Basement objects in the Detailed Ground Heat Transfer group
  • Modify this file by removing "GroundHeatTranfer:Basement:" from all component names
  • Run the file in Basement using EP-Launch-Utilities
  • Take the temperature results from the Basement run - Calculate one representative temperature per month that, applied on both underground walls and basement floor, should result in the same heat transmission (considering areas and temperature differences)
  • Insert these temperatures in a short idf file only containing the Site:GroundTemperature:BuildingSurface object
  • Add this file to the main model using the method in my previous answer

Now I can continue work in the OpenStudio model and run simulations without bothering to much about the basement heat transfer as long as I do not modify parameters related to it. I realise that this could have been done more elegant, but this is good enough for my purposes anyway.

2015-03-26 06:56:46 -0500 received badge  Scholar (source)
2015-03-23 05:25:24 -0500 received badge  Student (source)
2015-03-23 05:07:38 -0500 asked a question Ground heat transfer data and similar detailed input in Open Studio

I am learning OpenStudio and EnergyPlus and are practising by creating a building model in OpenStudio and the SketchUp application.

To set input data regarding ground heat transfer in my model, I first thought that I should export an idf-file from OpenStudio, set the input in the idf-file (Detailed Ground Heat Transfer section for example), and then reimport the idf-file to OpenStudio to run the simulation and/or continue to work on my model. However I understand that I lose parts of my model during idf export-import.

I understand that I could write a measure using Ruby that could allow me to insert the heat transfer data from OpenStudio. This would however require some work.

I could of course finalize my modelling in OpenStudio, export an idf-file, add further details in the idf-file and run the simulation using Energy Plus-EPLaunch only. The added idf-detailes would then need to be re-entered if I would go back to OpenStudio and /or the SketchUp application for modification.

Are there any better options if I want to set detailed Energy plus input data, not handled byOpenStudio, and still be able to continue modelling and simulation in OpenStudio?